I read your original post. If you can live with hearing ATC and the cell at
the same time, without priority for ATC, there's a solution for about $15
which I have used very successfully. Get an earpiece for you phone that has
the microphone built into the earbud. These may be a little hard to find
now because the bomm variety is all the rage. Jabra used to make one which
came with different colored earpieces to customize the fit in your ear.
Just slide that under the cup of your headset. The sidetone in your headset
transmits the voice well. I used this setup in Canada where cell phone use
in the air is legal.

I need it for important calls just in case and for passengers, dont worry!